Rebatching to maximize medicinal, color and fragrant properties of extracts.

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Garden Gives Me Joy

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I want to maximize medicinal, color, and fragrant properties of extracts in superfats and other water-soluble plant-based extracts. It seems that NaOH and heat degrade these properties. I'm wondering whether rebatching / double milling my plain soap is a solution. If my thinking is correct, how best should I approach this?

Initial process: Should I use CP or HP?
  • Why are cold processed mostly / often / only mentioned for rebatching?
  • Can't I get the same results if I speed things up with the HP?

How might HP work?
  • If I used the HP, should I somehow do things differently re superfatting, water content or other variables during the initial milling process?
Example.
  • Should I cook with extra water to emulate the CP?
  • Should I cure the soap faster by molding it in a particular way?
  • NaOH seems highly responsible for the loss of extract properties. On that basis, would adding all superfat upfront, even at the end of the initial milling using the HP method, help to neutralize the NaOH faster before rebatching? ... or would it be better to add the superfact during the rebatch process if HP was used for the initial milling?

Temperatures for adding Essential Oils?
  • Should I use the 'flash point' as a guide for the ideal temperature at which I should add easily-evaprated top note oils to minimize their evaporation? ... and before the batter seizes up? For instance, tea tree oil has a FP of 59 degrees Celsius. Should I aim to add the oil at around 55 C (a little less because the mass of the soap may continue to heat up after being repoured)?

Thanks so much in advance for answering my questions.
 
Hey @Garden Gives Me Joy !

There are a lot of questions here.. I'm not sure if I completely understand what you want to ask, but I'll try to answer:
1. Medicinal properties - general consensus on the forum is that even if they stay intact in soap (which is questionable since soap has a high pH even after cure) the contact time of soap on skin is too short to have any real effect and they're better used in lotions etc.

2. Colors - I've experimented a fair bit with natural/plant colorants and adding heat does seem to make them degrade faster (especially green colorants) I would also advise to make an extract of some kind (oil infusion, alcohol tincture or clay soaked in alcohol tincture -be sure not to add alcohol to CP soap, so you have to be a bit careful about your methods with alcohol. You could do a 50/50 water/alcohol tincture and evaporate off the alcohol or add a 100% alcohol tincture after hp cook)
I have to admit most of my color experiments have been CP. Keeping your soaps in the dark will help with color retention.

3. Scent (eo's). I once compared 3 different eo's cpop, cpop with anchor and added after hp cook. The latter seemed to hold scent better for citrussy top notes, but lately I've been wondering if water content in a soap might affect scent fading (no results on that yet) and HP soaps generally have more water to keep the batter fluid. So not sure yet if HP (or rebatch for that matter) would be a better option for scent retention. Keeping your soaps well packaged and away from airflow after the initial 4-6 weeks cure will help with scent retention.

4. CP/HP/rebatch You can rebatch a HP soap the same way you rebatch CP soap, but why not just add everything after HP cook? That basically has the same effect of not having the lye react with stuff (though adding after cook is not always the best way to go for plant colorants, but neither is rebatch).

5. Flashpoint for as far as I know is a safety measure for transport. I think it has something to do with the temp at which it is more likely to catch on fire. It's a good idea to have the pure oils stay below it, but it doesn't say anything about when the oil will evaporate (I'm a bit iffy on this one, so if someone with more knowledge chimes in that would be great)

If you want some extra reading, here's my experience with natural (green) colorants: Natural green colorants experiment
Mobjack Bay's experience with madder tincture and madder tincture soaked clay in cp soap (this whole thread is super interesting to read!). What’s the madder with my madder?
Here's my experience with alcohol infusion after HP cook
https://www.soapmakingforum.com/threads/plants-infused-in-alcohol-added-after-hp-cook.75970/And with clay soaked in alcohol added to cp
https://www.soapmakingforum.com/threads/clays-colored-with-plants.78067/And finally my not so great experiment with eo retention:
https://www.soapmakingforum.com/threads/does-anchoring-fading-eos-work.71364/
 
Thanks for your thoughtful response.

Hey @Garden Gives Me Joy !
1. Medicinal properties - general consensus [..] is that even if they stay intact in soap (which is questionable since soap has a high pH even after cure) the contact time of soap on skin is too short to have any real effect and they're better used in lotions etc. [...]
3. Scent (eo's). [...] added after hp cook [...] seemed to hold scent better for citrussy top notes, but lately I've been wondering if water content in a soap might affect scent fading (no results on that yet)
4. You can rebatch a HP soap the same way you rebatch CP soap, but why not just add everything after HP cook? That basically has the same effect of not having the lye react with stuff [...]

Sounds like medicinal ingredients are best suited for leave-in products. I will start focusing more effort instead into infusing the herbal extracts into body butters, my next point of research as a consequent.

However, since I often have an abundance, including an excess that can be go otherwise plain soap by infusing it into the superfat, I will attempt adding it at the end of the HP (rather than during a re-batching which, as you rightly mentioned also involves heat, possibly comparable to that at the end of HP). Since HP will be less labor intensive and faster overall, HP is definitely more attractive.

Re Preserving More of the Fragrant & Sensorial Effects of Mint despite heat
Trying to make the best of sub-optimal circumstances, my lingering question is whether there is any way to somehow temporarily extend the molten / 'liquefied' state of completed HP soap while it cools to as near to room temperature as possible or only just above? If I could find a way, I would love to add the mint to cured soap at room temperature. If there is a way, please enlighten me. I thought that, if the batter is stiffening, I might add a tiny amount of extra water at room temperature and then use an electric beater (somewhat like what people might do with whipped cream soap)? Sounds feasible?

Re water whether / how water affects scent retention
A batch of bar soaps had way too much humectant and never hardened. I was able to 'rebatch' it completely with only a fork at room temperature while I combined mint oil with great fragrant and sensorial results in the final forever soft product. It retained more mint than another batch that received more mint at apx 45 deg C. ... or was it the other ingredients like clay and sulfur in that soap? ???


Re Wanting Natural Green

Hey @Garden Gives Me Joy !
[...]
2. Colors - I've experimented a fair bit with natural/plant colorants and adding heat does seem to make them degrade faster (especially green colorants) [...]
Keeping your soaps in the dark will help with color retention.
[...]
[Best results of spirulina in natural green experiment: Natural green colorants experiment ]

Nice pretty result re fresh spinach and dried alfalfa in this one-month old soap discussed eventually in the threads you mentioned. So perhaps the learning point is that, although the results are not long lasting, a combined approach with fresh + dried material might render better green results, albeit short-lived?
 
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any way to somehow temporarily extend the molten / 'liquefied' state of completed HP soap while it cools to as near to room temperature as possible or only just above?
A method often used to keep HP liquid for swirls is adding 1T of yoghurt per pound of oils after cook, then some water (e.g. start with 2 parts water to 1 part lye and add another part after cook, so you have a 3:1 water:lye concentration in total - that's about the maximum I would go for). I recently added goat's milk after cook and thought it helped making the soap a bit more fluid than water, but I should compare water and goat's milk a few times to see if it's true.
An electric beater will add air and make it cool down/harden faster. I never used it on HP, but expect mixing with a hand whisk will help you control cool down better so you can add your ingredients at the balance point of still workable, but cool enough soap batter (you'll have to experiment to find your sweet spot and it might depend on your recipe as well)

... or was it the other ingredients in that soap? ???
Your guess is as good as mine at this point..

combined approach with fresh + dried material might render better green results, albeit short-lived?
My experience with alfalfa hasn't been too successful, so I think in the soap you mention it will mainly have been spinach that contributed to the pretty green color. I've added frozen fresh pandan to cp with good results (still a pretty green at 6 months), so that might work for spinach as well. Most of the powders I add turn brown in the end (spirulina tends to hold up a bit longer for me, though it fades a lot for others). My alcohol infusions added after hp cook hold up well, they have very vivid green colors (they change a bit over time, but keep a nice color, they're now 8months old) and an oil infusion of matcha is holding up for 7 months now (all stored in a dark basement), which is why I start to gravitate towards extracts instead of powders.
Also, thank you for reminding me of spinach, I want to try it out sometime!
 
Thanks for another informative response.

Re extending the molten state of HP bar soap (for swirls, etc) via the 'yoghurt method'
Wow re yoghurt method for swirling HP! So if I understand correctly, this yogurt method involves additional water and yoghurt, but no additional lye? Being vegan however, I'll try an oily milk --OR-- oat milk with oil, ie oil in excess of the superfat. Have I understood the method correctly? Despite being vegan, I would love to understand the concept regardless.

Add before cooking
  • 2 parts water to 1 part lye (ie 1 parrt of water in excess of the normal recipe amount? ... but no excess of lye. Right?)
Add after cooking
  • 1T of yoghurt (or goat milk) per lb of oils
  • 1 part water (to total 3:1 water : lye concentration, ie water in excess of the normal recipe amount).


Re Other ingredients that might have helped the fully cured soft soap I rebatched at room temperature.
The main other ingredient was sulfur, at 10% of oils. Another albeit very small amount was kaolin clay. [My currently odd internet connectivity allowed me to edit the original post offline before seeing your question].

Re natural green
I also make oil infusions via medical grade alcohol which I evaporate off as you had suggested. I must however add to my list of things to do is to freeze after curing in a completely dark space.
 
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Yes, you understood the yoghurt method correctly! This is with the max amount of water, lots of people use less. The soap will warp during cure, so only plane and bevel after a few weeks cure. Soy yoghurt works a charm, so if you can get that it would be a good substitute (I often use it, I'm not vegan, but somehow prefer the taste of soy yoghurt to regular. My taste buds are weird)

Using sulfur in soap is new to me, I have no idea how it will influence soap, so can't help you there.. sorry!

I don't freeze my alcohol infusions before adding to the soap. I only freeze fresh greens added to cp at trace (pandan pureed with water and I think I'd do the same with pureed spinach). Obviously you could try, but adding frozen things to HP might make it harden too fast, so try it on a small batch first;)

Eta: when adding colorants after hp it's not necessary to evaporate off all the alcohol (I let some evaporate to get a stronger infusion). Alcohol can react badly in cp, but not after hp cook.
 
Since HP will be less labor intensive and faster overall, HP is definitely more attractive.

I don't understand how HP is less labor intensive? The steps are basically the same, but with the added step of babysitting the soap while it's in the crock. That's why I'm not a fan of doing HP, myself-- I didn't like having to monitor it. I like that I can mix everything together, pour it all into a mold, and then forget about it until I unmold.

Yes, you can cut faster, but it will require the same cure time as CP.

I'm not trying to discourage you from HP. There are a lot of people who prefer it over CP.
 
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